结构间隙对芳纶纤维增强复合装甲结构抗侵彻性能的影响

采用由5 mm厚的前置钢板、60 kg/m²面密度的芳纶纤维增强复合材料层合板抗弹芯层、10 mm厚的后置钢板构成的夹芯式复合装甲结构,模拟舰船舷侧复合夹芯舱壁结构。根据面板与芯层间有无50 mm的间隙,将复合装甲结构分为无间隙式、后间隙式、前后间隙式3种结构型式。开展了复合装甲结构在质量40 g、最高初速约为1 630 m/s的高速圆柱体弹丸冲击下的抗侵彻性能实验,提出了钢质面板和芳纶纤维增强复合材料层合板芯层的破坏模式,研究了复合装甲结构的抗侵彻机理,对比分析了同一穿甲载荷冲击下3种复合装甲结构的抗弹性能。结果表明：前置面板的破坏模式主要为剪切冲塞;面板与芯层之间的间隙对芳纶纤维增强复合材料板的破坏模式及钢质背板的变形量影响较大、对前置面板影响较小;同一穿甲载荷冲击下,间距的存在有利于复合装甲结构综合抗侵彻性能的提高。     

江坪河水电站围堰防渗方案试验研究

针对江坪河电站大坝上下游围堰地质条件,进行混凝土防渗墙及高压旋喷灌浆两种防渗方案的试验研究,试验中塑性防渗墙的防渗效果较为明显,适应性及可操作性较强,可作为上下游围堰的防渗方案。     

Corrosion mechanism and behavior of high-velocity arc-sprayed Al–Ti–Si–RE coating in a simulated deep sea

The corrosion protection of deep-sea equipment using the economical method of thermal spraying has become a research hotspot. This study investigated the corrosion behavior of high-velocity arc-sprayed Al–Ti–Si–RE coating in a simulated deep sea with regard to microstructures, compositions, and electrochemical measurements. Results showed that the Al–Ti–Si–RE coating has excellent corrosion resistance at high hydrostatic pressure (HP). HP plays an important role in the anodic reaction of the coating, whereas dissolved oxygen (DO) mainly affects the cathodic reaction. HP accelerates the dissolution of the coating's passive film, which results in steady corrosion. The amount of corrosion products depends on DO. The corrosion of the self-sealing coating is inhibited in low DO when steady corrosion is achieved.     

Dependence of the Depth of Penetration on the Parameters of an Elongated Striker

On the basis of numerical simulation of the process of penetration of impact-destructible elongated metallic strikers into impact-destructible thick plates, we study the influence of the geometric shape and material of the striker on the depth of penetration and the possibility of through penetration. The depth of penetration is analyzed for the case where the impact velocity approaches the hydrodynamic limit.     

高水头大流量泄洪消能研究：“八五”国家科技攻关专题简介

本文扼要地介绍了国家“八五”科技攻关“高水头大流量泄洪消能研究”专题所取得的主要成果．根据小湾在可行性研究阶段所面临的一系列水力学问题，重点研究了泄洪消能布置及泄水建筑物体形优化，下游平衡冲深，水垫塘水力特性及体型优化，坝身泄洪引起的坝身振动，５０ｍ／ｓ级高速水流空化空蚀及减蚀措施，泄洪雾化影响及防护措施等方面的问题．并结合漫湾电站泄洪进行水力学方面的原型观测，为高坝建设积累经验．经过几年来的艰苦努力，取得了一系列突破性的科研成果，圆满地完成了攻关任务，其中大部分攻关成果巳为小湾设计采用．专题经专家鉴定为整体达国际先进水平，并有部分成果为国际领先水平．     

Effect of particle impact on residual stress development in HVOF sprayed coatings

The application of thick high-velocity oxyfuel (HVOF) coatings on metallic parts has been widely accepted as a solution to improve their wear properties. The adherence of these coatings to the substrate is strongly influenced by the residual stresses generated during the coating deposition process. In an HVOF spraying process, due to the relatively low processing temperature, significant peening stresses are generated during impact of molten and semimolten particles on the substrate. At present, finite-element (FE) models of residual stress generation for the HVOF process are not available due to the increased complexities in modeling the stresses generated due to the particle impact. In this work, an explicit FE analysis is carried out to study the effect of molten particle impingement using deposition of an HVOF sprayed copper coating on a copper substrate as an example system. The results from the analysis are subsequently used in a thermomechanical FE model to allow the development of the residual stresses in these coatings to be modeled. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

Microstructure and mechanical properties of HVOF sprayed nanocrystalline Cr3C2-25(Ni20Cr) coating

The objectives of this work are to deposit nanocrystalline Cr₃C₂-25(Ni20Cr) powder by thermal spraying and to compare the performance of this coating with that obtained using conventional powder. Towards that purpose, Cr₃C₂-25(Ni20Cr) powders with nanocrystalline grain size and with conventional grain size were deposited using OSU-SJS high-velocity oxyfuel (HVOF) system. The microstructural features, such as morphology of the coated surface, thickness of the coating, the interface of the coating with the substrate, distribution of various phases, and grain sizes etc, were characterized with the help of optical microscope, scanning electron microscope (SEM), and transmission electron microscope (TEM). The amount of oxide phases and pores were determined by means of image analyzer. The presence of various phases was identified by x-ray diffraction (XRD) technique. Hardness, elastic modulus, and indentation toughness were evaluated employing micro indentation technique. The results indicate the presence of three different zones containing only orthorhombic Cr₃C₂ phase, FCC NiCr phase, and mixture of Cr₃C₂ and NiCr phases in, both coatings. The grain sizes in the nanocrystalline coating were in the range of 80 to 100 nm. Nanocrystalline coating exhibits 20% increase in hardness, 40% decrease in surface roughness, and comparable fracture toughness and elastic modulus with respect to conventional coating.     

Determining the strength of filled epoxy from ballistic experiments

This paper analyzes the results of experiments with impact of metal spherical impactors on cylindrical targets of epoxy (filled with Al₂O₃ microparticles and without the filler) performed in a ballistic range. Impact velocities were limited to a range of 0.6–1.1 km/sec since higher velocities led to complete destruction of the targets. Impacts at the velocities considered produced channels of an almost cylindrical shape with the impactor stuck at the end of the channel. The strength of filled epoxy is estimated using the previously established dependence of the channel depth on the impact energy, the ratio of the densities of the impactor and target materials, and the tensile strength of the target material. It is found that at a mass fraction of the filler equal to 0.4, the strength of the target increased by a factor of approximately 1.5–2. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 5, pp. 123–130, September–October, 2008.     

Design and implementation of a high-velocity projectile generator

An explosively formed projectile (EFP) is designed as a high-velocity projectile generator to be used in a field test in which an equivalent fragment impacts on an equivalent tactical ballistic missile warhead. The formed slug of the EFP is ≈45 g and has a velocity of around 2500 m/sec. EFP detonation and slug forging are numerically simulated using an LS-DYNA3D finite-element code to optimize the design parameters of the EFP. Tests with determining EFP velocity and mass are performed to confirm the preliminary design and evaluate the EFP performance. A flash X-ray facility is employed to measure the profile and the velocity of the EFP slug. The high-velocity projectile generator developed herein can be used in verifying the lethality of the antitactical ballistic missile warhead against tactical ballistic missile. It is also useful for research of the resistance of military fortifications and nuclear power plant containment structures to penetration. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 123–131, March–April, 2007.     

高速透气阀压力流量特性实验和入级型式试验

研究阐述了透气阀结构及工作原理,并以DN200型高速透气阀为例,设计了透气阀实验使用系统及实验方法、步骤,揭示了透气阀的压力-流量特性。研究结果表明:正压阀开启压力为14.1 kPa,正压阀关闭压力为10.0 kPa;真空阀开启压力为-3.5 kPa,真空阀关闭压力为-2.6 kPa。正压阀瞬间的排气速度高达42 m/s,符合各船级社规范、SOLAS公约和IMO规则对应的章程条款要求。同时发现:透气阀设定压力通常设定正压阀为14.1~21.4 kPa、真空阀为-3.5~-7.01 kPa范围内,在规定值内即阀瓣起跳。